1. Field of the Invention
The present invention relates to network repeaters, more specifically to an IEEE 802.3 compliant repeater providing a bridge between two media domains operating at respective data rates.
2. Background Art
Network repeaters are typically used as a bridge between network nodes, for example network stations serving as data terminal equipment (DTE) on different network media. Repeaters provide the advantage of extending the physical distance between network nodes by receiving a data packet from one network medium, reconditioning the physical signal, and outputting the data packet to a second network medium. The repeater may also forward carrier sense and collision signals, effectively extending the collision domain of one medium onto the second medium. Repeaters in connecting network nodes on different network media have conventionally been configured to connect only networks operating at the same transmission rate. One problem encountered in higher-speed networks, for example 100 Mb/s IEEE 802.3 networks, is the identification of a link, between the network repeater and a remote network node on one of the network repeater ports, having a poor level of integrity. In particular, there is a need to discover links between a repeater port and a network node that are not performing up to specifications, for example due to a poor cable connection or condition, a faulty network interface device at the remote node, etc.
One proposal for handling link failure is by using network management capabilities, for example, a remote management agent (i.e., network manager) configured for monitoring and controlling operations of the repeater and the network nodes. For example, the remote management agent uses a management protocol to transmit management information between the repeater and the remote management agent. However, such an arrangement necessarily relies on a management agent, and hence is inapplicable in unmanaged network. Moreover, the monitoring of links by a centralized management agent increases the complexity and processing requirements of the management agent. For example, the management agent may need to determine link integrity by flooding the network with test packets, monitor the responses from the network nodes, and reconfigure each node separately. Such an arrangement is both inefficient and expensive from a resource management standpoint.
In addition, reliance on a centralized management agent creates substantial cost concerns. Hence, network customers are often forced to choose between managed networks having a high cost and lower-cost unmanaged networks incapable of handling link integrity problems that occur at higher data rates.
There is a need for an arrangement for interconnection of different speed network nodes using a repeater, where the link integrity between a repeater and the network nodes can be reliably monitored without the necessity of a network manager.
There is also a need for an arrangement in a network having a repeater for monitoring the link status of high speed data links, and selectively changing a selected high speed data link to a slower data rate based on detection of a marginal or unacceptable link status on the selected high speed data link and user configuration signals supplied locally to the repeater (i.e., without the necessity of a network manager).
There is also a need for an arrangement in a network repeater for monitoring the link status of high speed data links, where the error rate of link can be reliably determined despite the presence of transient errors that may otherwise create the perception of an artificially high error rate.
These and other needs are attained by the present invention, where network repeater monitors each repeater port link in communication with a remote network node at a corresponding data rate. The network repeater monitors each link by counting a detected number of symbol errors relative to a prescribed threshold. The network repeater, upon detecting a link having a poor integrity as measured by the prescribed threshold, may selectively reconfigure the link, based on user configuration signals supplied to the network repeater, by reducing the data rate on the network medium to provide a more reliable link having a reduced number of symbol errors.
According to one aspect of the present invention, a method in a network repeater of controlling transmissions includes establishing a link with a remote network node at a prescribed data rate via a network medium, monitoring the link by counting a detected number of symbol errors; determining an integrity of the link based on the detected number of symbol errors relative to a prescribed threshold, and selectively reducing the data rate on the network medium to a reduced data rate in response to the detected number of symbol errors exceeding the prescribed threshold and based on a configuration signal supplied to the network repeater. Monitoring the link by counting a detected number of symbol errors enables the network repeater to determine the link integrity of each network repeater port in a relatively simple manner without the necessity of a network manager interfering with network activity. Moreover, the selectively reducing step enables an individual user to manually configure the network repeater for data rate reduction by supplying the configuration signal, eliminating the need for a network manager.
Another aspect of the present invention provides a network repeater having a plurality of repeater ports, configured for sending and receiving data packets between remote nodes via respective network media. The network repeater includes a first repeater core configured for sending and receiving data packets between a first group of the repeater ports according to a first data rate, a second repeater core configured for sending and receiving data packets between a second group of the repeater ports according to a second data rate slower than the first data rate, an auto-negotiation unit configured for selecting one of the first and second data rates, according to stored configuration information, for establishment of links between the repeater ports and the respective remote network nodes via the respective network media, a symbol error detector for detecting a number of symbol errors relative to a prescribed interval on at least one of the links operating at the first data rate, and a controller. The controller has a configuration register for storing the configuration information supplied from a user configuration signal, and is configured for selectively changing the at least one link from the first data rate to the second data rate based on the number of symbol errors reaching a prescribed threshold and according to the stored configuration information. The symbol error detector can detect the number of symbol errors on at least one link, enabling monitoring of each link without the necessity of an external management agent. Moreover, the controller enables the link to be reduced to a lower speed in the event that a higher number of symbol errors are detected based on stored configuration settings, eliminating the necessity of an external management agent to monitor link integrity or execute more complex routines in an effort to overcome poor link integrity conditions.
Additional advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.